The present invention relates to an electronic watch comprising functions which are dedicated to the implementation of diving. More precisely, the diving watch according to the present invention is of the type comprising a sealed housing containing a clock movement which is surmounted by a dial, the watch comprising at least first graduations, said clock movement comprising electronic circuits which are able to produce time signals intended for motor means which control respectively at least a first and a second analog display organs, said display organs being disposed above the dial in order to display the current time in a first time operating mode, the watch comprising furthermore a pressure sensor which is able to produce electrical signals which are representative of the surrounding pressure and to supply said signals to said electronic circuits, the diving watch having at least a second operating mode, or diving mode, in which a display of data relating to the practise of diving is provided.
Similar products have already been described in the prior art. The patent U.S. Pat. No. 4,783,772 in particular describes an analog electronic watch provided with a pressure sensor which permits it to display data relating to the practise of diving. These data, and also information relating to additional functions, such as an alarm for example, are displayed on an additional liquid crystal screen, disposed on a twelve-hour basis on the dial of the aforementioned watch.
In any event, the nature of the information available on the described product is limited to information of the type of the momentary depth, duration of the dive in progress, maximum depth attained. As a result, the use of this information in safety terms requires using independent decompression tables in order to define the parameters of the ascent, in particular the determination of the maximum duration during which the user can remain submerged before having to effect at least one decompression stage.
Likewise, no information is given with respect to the decompression stages to be effected possibly during the ascent from a dive. Furthermore, the readability of the liquid crystal screen is limited due to its small size, in particular in underwater conditions.
A first object of the present invention is to reduce the previously mentioned disadvantages of the prior art by making available a diving watch which indicates to its user information relating to his safety during his dive.
Another object of the invention is to propose a diving watch which permits its user to observe the aforementioned information very easily, in other words to produce a diving watch which has good readability of this information.
With this object, the invention provides in particular a diving watch of the type indicated previously, characterised by the fact that said first graduations serve in particular for indicating a depth, in that said electronic circuits comprise first means for controlling the first analog display organ, in said diving mode, in order to indicate the momentary depth in conjunction with said first graduations, and in that said electronic circuits likewise comprise second means which are able to define almost continually a minimum depth which is not to be exceeded by the wearer of the watch during the ascent from a dive, calculated from a substantially continuous decompression algorithm, and to control said second analog display organ in order to indicate said depth which is not to be exceeded in conjunction with said first graduations substantially in real time.
It is likewise provided that the second means of the electronic circuits are furthermore able to define discontinuous decompression parameters comprising at least one stage to be effected during the ascent from a dive, calculated from the algorithm, a stage being in particular defined by its depth and its duration, and to control sequentially the second display organ, in the diving mode, in order to indicate, in the first instance, the depth of at least one stage to be effected during the ascent in conjunction with said first graduations and in order to indicate, in the second instance, that the diver can resurface.
In the case of a plurality of decompression stages to be observed during the ascent from a dive, means are provided in order to control the second display organ in order to indicate their respective depths in a sequential manner, which will be described in detail subsequently in the present application.
It is important to note that, insofar as the display of the data relating to the depth is produced by analog display organs which are used normally for displaying the time, excellent readability is ensured. Furthermore, as regards the adopted structure, relative reading of the respective positions of the display organs is possible and gives a certain synergy. Indeed, during the ascent from a dive, the second display organ is positioned at the depth of the deepest decompression stage to be effected, the first display organ indicating the momentary depth.
The determination of the parameters of the respective decompression stages is produced on the basis of diverse algorithms obtained following numerous medical studies related to the study of decompression of gases in the human body. The choice of algorithm is of little importance either for understanding of the present invention or for its implementation by the person skilled in the art, who will be able to choose an algorithm from the most recent which are generally recognised in the sphere of diving.
It will be possible for example to use an algorithm based on the models of Haldane, Bxc3xchlmann or even on one of their variants, taking into account microbubbles, such as for example Yount""s VPM (xe2x80x9cVarying Permeability Modelxe2x80x9d) or Wienke""s RGBM (xe2x80x9cReduced Gradient Bubble Modelxe2x80x9d) models.
These algorithms also permit decompression of the gases dissolved in the body of the diver to be effected during the dive in a continuous manner, in other words without effecting a decompression stage but observing particular conditions of ascent. With this object, these algorithms define a minimum pressure continually, from which one can deduce a minimum depth to which the diver can be exposed without putting himself in danger dependent upon his physiological state.
Thus, whichever type of algorithm is adopted for the production of the watch according to the invention, the diver can easily verify that he is at a depth which presents no danger to his health by a simple reading of the relative positions of the two display organs. The diver must bear in mind, during his ascent, that the position of the first display organ must not rise, in the anticlockwise direction of rotation, beyond the position of the second display organ. This reading is advantageous insofar as it is more intuitive than the reading of an indication placed on a dial above which a display organ is situated. Likewise, this reading is more intuitive than the reading of two distinct pieces of information which are displayed on one or two liquid crystal screens and must be correlated.
In general, means are provided in order to actuate, from the time operating mode, a diving operating mode in an automatic manner. It is obviously possible to use actuation of the manual type for this last operating mode, for example by pressing a push button.
In a preferred embodiment of the present invention, means are provided for controlling the minute hand in order to display the depth substantially in real time, and the hour hand in order to display the information relating to the dive, in particular that which relates to the safety of the wearer of the watch or diver.
The watch according to the invention preferably has second graduations comprising at least a first zone which permits an indication to the diver, in conjunction with the hour hand, that his body is undergoing minor physiological modifications with respect to his normal state, these modifications being related to the performance of diving. It is obvious that this scenario applies when the diver is at the surface after having ascended from a dive or when he is at the start of a dive, the history of which, in terms of depth and duration, does not require that a decompression stage be effected during the ascent.
In particular, means are provided for positioning the hour hand in the first zone of additional graduations in order to indicate to the wearer of the watch the value of the altitude which must not be exceeded after the dive in progress, this value being dependent upon the above-mentioned physiological modifications. Furthermore, the position of the hour hand relative to the ends of the first zone, during the dive, can permit the diver to assess approximately the maximum remaining duration before having to effect a decompression stage during the ascent.
Indeed, as long as the diver does not descend more than a few meters in depth, he can stay submerged for several hours without having to respect a decompression stage during the ascent, assuming that the dive in progress is the first for at least about ten hours. Means are provided for measuring the surrounding pressure and linking these pressure measurements to the time and for deducing therefrom, by calculations based on an algorithm, the maximum duration remaining without having to effect a decompression stage during the ascent.
In a preferred variant, the diving watch according to the present invention comprises at least one external control member and at least one liquid crystal display screen, preferably two. Means are likewise provided for controlling these liquid crystal screens in order to permit the indication of additional information to the diver, the nature of this information varying with the operating modes.
It is likewise provided to implement a third operating mode, or historical mode, which is accessible by operating a control member from the time function. In the historical mode, means can be provided for actuating the hour and minute hands to reproduce their actions from one of the last dives at an accelerated rate. It can likewise be provided to display, on the two liquid crystal screens, respectively the maximum depth attained and the total duration of the dive.